When overweight people included two servings of purple potatoes a day in their diet for a month, they not only reduced their blood pressure, they also didn't gain weight in the process, a small study shows.

In the study, published online in the Journal of Agricultural and Food Chemistry, researchers tracked 18 middle-aged adults. Half of them were asked to eat the skin and flesh of six to eight small purple potatoes at lunch and dinner for four weeks, while the others did not add the microwaved taters to their meals.

During the second month of the study, the groups switched regimens.

Participants were given Purple Majesty potatoes.

Compared to those who went spud-free, purple potato eaters had on average drop of slightly more than 4% in diastolic pressure (the bottom number in a reading) and a drop of more than 3% in systolic pressure (the top number).

Since 14 out of 18 participants had high blood pressure and nearly all of them took medication for it even during the study, a small blood pressure decrease may help lessen their odds for heart disease.

Although potato eaters took in more calories compared to adults given no potatoes, their weight didn't change. That's good news because seven participants were obese and six were overweight.

In Korea, purple-colored spuds are considered a folk remedy for weight loss.

Purple Potato Perks

The researchers suggest that purple potatoes are an effective agent to reduce blood pressure and lower the risk of heart disease and stroke in people with high blood pressure -- without weight gain.

As for why the colorful spud may help the heart, scientists say the purple vegetable has many of the same healthful plant pigments as purple fruits. It's rich in antioxidants, such as anthocyanins, carotenoids, and phenolic acids, which may reduce chronic inflammation linked with heart disease and stroke.

Pigmented potatoes also have high amounts of chlorogenic acid, a substance shown in animal studies to reduce elevated blood pressure.